refactor: remove dead session code

src/beaver_gateway/storage/models.py

@@ -1,9 +1,15 @@
-"""SQLModel tables — see PRD §9.
+"""SQLModel tables.
 
-Three tables, all flat, no relationships modelled yet (Phase 4 talks
-about ``actor`` and ``agent_name`` as strings — joining audit→token by
-name is fine at this volume; we'll introduce FKs when the admin UI
-actually demands them).
+Two tables, both flat, no relationships modelled yet (``actor`` and
+``agent_name`` are stored as strings — joining audit→token by name is
+fine at this volume; we'll introduce FKs when the admin UI actually
+demands them).
+
+A ``Session`` table originally lived here for live-session
+observability. It was dropped after we decided the gateway stays
+stateless about identity (claude-code-api's in-memory fingerprint pool
+is the source of truth) and that conversation persistence belongs in a
+future Obsidian-sync frontend, not a sessions table.
 
 Datetimes are stored UTC; we set ``default_factory`` rather than relying
 on DB defaults so SQLite + Postgres behave identically. Every row that
@@ -39,23 +45,6 @@ class Token(SQLModel, table=True):
     revoked_at: datetime | None = Field(default=None)
 
 
-class Session(SQLModel, table=True):
-    """Mirror of one live ``claude-code-api`` session.
-
-    The id is the ``session_id`` claude itself assigns on the first
-    turn; we don't generate it. Rows here are for admin observability
-    (live count, last activity) — the actual pool lives in
-    ``claude_code_api.ClaudeCodeBackend`` and is the source of truth.
-    """
-
-    id: str = Field(primary_key=True)
-    agent_name: str = Field(index=True)
-    fingerprint: str = Field(index=True)
-    created_at: datetime = Field(default_factory=_utcnow)
-    last_active_at: datetime = Field(default_factory=_utcnow)
-    closed_at: datetime | None = Field(default=None)
-
-
 class AuditLog(SQLModel, table=True):
     """Append-only record of who-did-what.
 
@@ -77,4 +66,4 @@ class AuditLog(SQLModel, table=True):
     detail_json: str = Field(default="{}")
 
 
-__all__ = ["AuditLog", "Session", "Token"]
+__all__ = ["AuditLog", "Token"]